May 25 – 29 , 2015, Dagstuhl Seminar 15221

Multi-disciplinary Approaches to Reasoning with Imperfect Information and Knowledge - a Synthesis and a Roadmap of Challenges


Igor Douven (Paris-Sorbonne University, FR)
Gabriele Kern-Isberner (TU Dortmund, DE)
Markus Knauff (Universität Gießen, DE)
Henri Prade (Paul Sabatier University – Toulouse, FR)

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Dagstuhl Report, Volume 5, Issue 5 Dagstuhl Report
Aims & Scope
List of Participants
Dagstuhl's Impact: Documents available
Dagstuhl Seminar Schedule [pdf]


This multi-disciplinary seminar with attendees from computer science, philosophy, and psychology addressed typical problems that smart and intelligent systems in real-world scenarios have to deal with both from formal and empirical points of view. Such systems have to face, in particular, the problem of reasoning with uncertain, imprecise, incomplete, or inconsistent (in short, imperfect) information which often renders more classical, i.e., strict or deductive methods obsolete or fallacious. Reasoning with imperfect information plays a central role in practical deliberation and rational decision making. Models of human context-dependent reasoning that synthesise logical, philosophical and psychological aspects would be helpful for designing better systems. In psychology, an increasing interest in new formal methods for rational human reasoning under uncertainty can be observed, and on the other hand, philosophers and computer scientists have shown an increased attention to the experimental methods of psychology recently. In particular for computer scientists and AI researchers, it is becoming more and more interesting to see whether the systems they have been developing are materially adequate. A synthesis of rational reasoning with imperfect information that takes into account research done in artificial intelligence, but also in psychology and philosophy is needed for providing a clearer view of where we are and what are the pending issues both from computational resp. logical and cognitive viewpoints. This will help making intelligent systems more effective, and more helpful for their human users.

This seminar brought together researchers interested in rational and uncertain reasoning from a very broad scientific scope to present and discuss problems and approaches from different disciplines, consolidate common grounds, and initiate new interdisciplinary collaborations. The seminar took profit from the fact that computer scientists, philosophers, and psychologists have started quite recently to work in a common methodological paradigm with overlapping goals, converging interests, and largely shared research tools. The attendees identified challenges for new paradigms of rational reasoning, and discussed visions and foci for more interdisciplinary work.

The first day, the seminar started with (invited) survey talks on central cross-field topics, where each topic was addressed by two researchers from different disciplines:

  • Nonmonotonic reasoning and change of knowledge and beliefs
    Marco Ragni (CS/Psy), Hans Rott (Phil)
  • Uncertain reasoning and decision theory
    Wolfgang Spohn (Phil), Henri Prade (CS)
  • Argumentation and reasoning under inconsistency
    Ofer Arieli (CS), Ulrike Hahn (Psy)
  • General forms of human reasoning (e.g., analogical reasoning, interpolation, and extrapolation, case-based reasoning)
    Vittorio Girotto (Psy), Steven Schockaert (CS)

The schedule for the next days included both sessions where attendees could present and discuss their work with the audience, and time slots for discussion groups. The topics of the discussion groups were discussed in a plenary session, and four groups came out of that:

  • Topics of group 1: Philosophers' and psychologists' view on human reasoning, and what computer scientists can contribute to that; axiomatic systems vs. psychological models -- how do they fit?
  • Topics of group 2: Empirical implications of formal reasoning systems and vice versa
  • Topics of group 3: Combination/mixture of reasoning methods, qualitative vs. quantitative approaches; formal axiomatic systems are suitable for decision making(?)
  • Topics of group 4: Promises and problems of probability theory; reliability, coherence, higher order probabilities

Groups 1 and 2 joined after the first session due to the closeness of the discussed topics. On Friday morning, the results of the working groups were presented, and a final, lively discussion in the plenary session closed the seminar.

Summary text license
  Creative Commons BY 3.0 Unported license
  Igor Douven, Gabriele Kern-Isberner, Markus Knauff, and Henri Prade


  • Artificial Intelligence / Robotics
  • Semantics / Formal Methods
  • Verification / Logic


  • Uncertain reasoning
  • Conditionals
  • Non-monotonic logics
  • Belief revision
  • Similarity-based reasoning
  • Semantical frameworks
  • Formal epistemology
  • Philosophy of probability
  • Cognitive aspects of rational reasoning
  • Empirical studies on rational areas


In the series Dagstuhl Reports each Dagstuhl Seminar and Dagstuhl Perspectives Workshop is documented. The seminar organizers, in cooperation with the collector, prepare a report that includes contributions from the participants' talks together with a summary of the seminar.


Download overview leaflet (PDF).

Dagstuhl's Impact

Please inform us when a publication was published as a result from your seminar. These publications are listed in the category Dagstuhl's Impact and are presented on a special shelf on the ground floor of the library.


Furthermore, a comprehensive peer-reviewed collection of research papers can be published in the series Dagstuhl Follow-Ups.